Tracking fish with parasites and maths

How much fish move around is critical information for fisheries managers—for example they need to know if fish caught off Brisbane are a separate population to those caught off Cairns. Different tracking techniques, such as physical tags or genetic mapping, can be used but each method has its weaknesses.

A team of mathematicians is using pre-existing data on Spanish mackerel, using their hitchhiking parasites to track fish movements and model the populations.

Since some parasites can live for a long time in their host, they can be used as living ‘markers’. If particular parasites that are found only in specific areas turn up on a fish caught somewhere else, this parasitic collection helps tell the story of the fish’s travels.

It’s just one of the applications of the models that Dr Ross McVinish and Professor Phil Pollett are working on at the ARC Centre of Excellence for Mathematical and Statistical Frontiers.

“We’re looking at population models and trying to understand how individual characteristics affect the population as a whole,” says Ross. Both he and Phil are based at The University of Queensland.

Another study focus is how the spread of a disease can be limited by changes in a population’s migration – for example, the rate of infection in a city and how it changes with population density. How do you balance increasing the population in areas of low infection without also boosting the risk of the disease spreading further?